Overuse injuries in disorders of the central nervous system

Author(s): Wei-Han Tan, MD, Felicia Skelton, MD

Originally published:10/22/2013

Last updated:10/22/ 2013

1. DISEASE/DISORDER:

Definition

Overuse injuries are injuries to the musculoskeletal unit resulting from cumulative trauma.1 For many individuals with central nervous system (CNS) disorders, performing repetitive motions is a vital part of general mobility and activities of daily living (ADL). This can lead to repetitive microtrauma of bones, joints and soft tissues and can contribute to pain and increased functional limitations.2

Etiology

Pentland, et al describe the development of overuse injuries as a combination of individual factors such as genetics, previous trauma, and other co-morbidities and their interplay with behavior and lifestyle (conditioning and activities), age-related musculoskeletal changes, and environment (equipment, layout and design of home, etc).3

For many individuals with CNS disorders, the most common etiologies of these injuries result from altered biomechanics of weight bearing through joints (shoulders, elbows, wrists) not designed to sustain submaximal, repetitive motions or significant amounts of weight over time. Examples include upper limb activity with wheelchair propulsion, and transferring the body between surfaces. Additionally, as most environments are adapted to the able-bodied population, the individual in a wheelchair will be required to place joints in mechanically compromising positions, such as with overhead reaching, which may, over time, contribute to the overuse injury. Individuals with CNS disorders are also more likely to have muscle weakness, leading to relative imbalance between muscle groups that can lead to injury.

Epidemiology including risk factors and primary prevention

Most of the information on the epidemiology of overuse injuries comes from literature on persons with spinal cord injury (SCI). Some of the most common injuries include, by region:

Patho-anatomy/physiology

Overuse injuries most commonly affect the musculotendinous unit resulting in tendinitis, tenosynovitis, and/or muscle soreness. Other tissues that can be involved include: bursae (bursitis), bone (stress fractures), nerve (compression neuropathies), and cartilage (OA).1 As the consequence of repetitive microtraumatic overuse, injuries eventually lead to an impairment in the tissue’s ability to repair itself. This results in the formation of scar tissue in place of the proper tissue matrix (e.g., bone, tendon, muscle, or ligament), which results in a decreased tissue function overall.1 Physical stressors thought to be potentiating factors in overuse injury include level of force, posture, duration, contact stress, vibration and temperature.5

In general, overuse injuries develop over several months to years after the CNS injury or disorder, but vary by individual and situation. Several conditions related to using a wheelchair, and thus development of overuse injuries, have changed in the past 40 years. Wheelchairs are now lighter, and can be better customized to avoid postures that are believed to contribute to overuse and injury (posterior pelvic tilt, excessive neck flexion, prolonged shoulder abduction, internal rotation and extension).5 Changes in rehabilitation technique such as moving away from overhead trapeze transfers have also altered the natural history of these injuries.

Individuals, including those with cerebral palsy and spina bifida, who are lifetime wheelchair users, also face unique challenges. Yearly exams to assess range of motion, posture and proper equipment fit are part of regular health maintenance.8

Overuse injuries have an acute phase in which ongoing microtrauma is occurring, and more chronic phases characterized by maladaptive tissue formation, as above.

2. ESSENTIALS OF ASSESSMENT

History

Initial history should include a comprehensive evaluation of pain symptoms (onset, location, radiation, character, severity, alleviating/aggravating factors, typical activities or sports that bring on pain). Special attention should be paid to history surrounding inciting injury (as in spinal cord injury or traumatic brain injury), as concomitant musculoskeletal injuries are often overlooked.

Other items to be considered in the history are level of SCI (if present), previous diagnostic evaluations, previous treatments tried and whether or not they were efficacious, any recent changes in wheelchair use, the presence of spasticity, and changes in body mass index (BMI). Additionally, a review of the functional impact of injury on ADLs, vocation, community reingration, and recreation should be completed.

Probing questions to differentiate between types of pain (neuropathic, referred and mechanical) can be helpful. Mechanical pain from tissue injury can be reproduced with active, resistive or passive motion.

Screen for any history or pertinent symptoms that may point to a non-musculoskeletal source of pain (e.g., new or changing neurologic symptoms, symptoms of an inflammatory process, etc.)

Physical examination

As with any general musculoskeletal exam, inspection of the region in question for deformity and atrophy, palpation for point tenderness, range of motion (ROM) (both passive and active), and neurologic exam including manual muscle testing, sensation and reflexes, are key. It is often helpful to have the individual demonstrate a maneuver that reproduces the pain. Evaluation of spasticity and muscle imbalances are special considerations in this population.

Selected provocative maneuvers by potential diagnosis:

RTC tear: Empty can, Drop arm test

Impingement: Neer’s and Hawkin’s tests

Bicipital tendinitis: Speed’s and Yergason’s tests

Lateral epicondylitis: pain with resisted wrist extension

DeQuervain’s: Finkelstein’s test

Carpal tunnel syndrome (CTS): Phalen’s and Tinel test

Functional assessment

Exploring mechanics of transfer technique and wheelchair propulsion can be helpful, as well as evaluation of equipment, including wheelchair set-up and seating arrangement. Boninger et al suggest that the optimal position of a wheelchair’s rear axle is 2 inches forward of the shoulder.9

Laboratory studies

Blood tests are usually not necessary, unless something in the the history or physical prompts further evaluation of possible systemic causes for complaints (e.g., concern for inflammatory process). Electrodiagnostic studies may be considered to evaluate for carpal tunnel syndrome, ulnar nerve entrapment, radiculopathy, or to rule out other possible causes for pain.

Imaging

Imaging is often not needed initially, as majority of diagnoses can be made by history and physical examination. Plain radiographs of the area in question can be considered to rule out fracture or to evaluate for osteoarthritis. Diagnostic ultrasound may be of use, as well. If more invasive interventions such as surgery are considered, more extensive imaging can be considered. For example, for rotator cuff tears, MRI arthrograms are the most sensitive, and are helpful in operative planning.

Environmental

Details on the layout of the individual’s home, automobile and/or work environment, specifically amount of overhead reaching and transfering that must be done, can be helpful when considering activity modifications.

Social role and social support system

Strong social support and access to resources will be important when prescribing relative rest from likely essential activities, or in case of referral for surgery with long recovery times and periods of immobility.

Professional Issues

Gutierrez et al interviewed 80 persons with spinal cord injury with the WUSPI and several quality of life measures and found that shoulder pain intensity was inversely related to quality of life and physical activity scores.11 Ergonomic assessments of the workplace environment may offer alternative equipment or set-up that will decrease the particular overuse activity in question.

3. REHABILITATION MANAGEMENT AND TREATMENTS

Available or current treatment guidelines

Sidall provides a useful algorithm for assessing pain after spinal cord injury, including musculoskeletal pain from overuse.12 Many of those recommendations will be outlined below.

At different disease stages

New onset/acute

Goal at this stage is to control pain and inflammation while limiting further tissue damage.

One option in this stage may be transitioning to a pushrim-activated power-assisted wheelchair to prolong a person’s ability to use a mechanical wheelchair (MWC).13

At the point where pain becomes too severe or limits function in a way that makes it unsafe to perform certain activities, transitioning from a MWC to power mobility to preserve current function should be considered.

For certain diagnoses (e.g., CTS, RTC tears), surgery may be an option when conservative treatment has failed, but can have significant morbidities. Recovery times with periods of absolute or relative non-weightbearing could mean the difference between the patient being able to live independently and not.

Pre-terminal or end-of-life care

NA

Coordination of care

Concomitant evaluation with physical therapy and occupational therapy, especially in regards to functional transfers, push mechanics, adaptive equipment and wheelchair fit, can be helpful. Workplace assessments if available can also be considered to review set-up and suggest equipment/ workplace modifications to minimize joint stresses and injury.

Patient & family education

Proper body and push mechanics should be reviewed with family and caregivers, so that it can be reinforced with the patient at home.

4. CUTTING EDGE/EMERGING AND UNIQUE CONCEPTS AND PRACTICE

Cutting edge concepts and practice

Norrbrink, et al described an intensive exercise program to reduce musculoskeletal and neuropathic pain: subjects trained on a double-poling ergometer three times per week during a 10-week period, in small supervised groups. Each session lasted 50 min. and included a warm-up, four intervals of 6–7 min, followed by a cool-down. Improvements in both neuropathic and musculoskeletal pain complaints were seen.14